Mixing Homogeneity Research Articles

Inhomogeneous multi-parameter Lipschitz spaces associated with different homogeneities and their applications

This paper is motivated by Phong and Stein?s work in [11]. The purpose of this paper is to establish the inhomogeneous multi-parameter Lipschitz spaces Lip? com associated with mixed homogeneities and characterize these spaces via the Littlewood-Paley theory. As applications, the boundedness of the composition of Calder?n-Zygmund singular integral operators with mixed homogeneities has been considered.

Pointwise multipliers for inhomogeneous multi-parameter Besov and Triebel–Lizorkin spaces associated with mixed homogeneities

In this article, we obtain pointwise multipliers on inhomogeneous multi-parameter Besov and Triebel–Lizorkin spaces associated with mixed homogeneities.

Effect of electrostatically charged and neutral polysaccharides on the rheological characteristics of peanut protein isolate after high-pressure homogenization

Peanut protein is attracting increased research and application interest because of its high nutritional value and its functional properties. In this study, two different electrostatically charged (chitosan and xanthan gum) polysaccharides and a neutral polysaccharide (guar gum) were used to investigate the interactions between polysaccharides and peanut protein isolate (PPI) in an aqueous medium after high-pressure homogenization. The rheological properties of the polysaccharides, PPI, and polysaccharide-PPI mixtures were characterized by continuous shear, frequency sweep, and temperature sweep measurements. The shear viscosity of the homogenized samples followed a power law model (R2 ≥ 0.992). High-pressure homogenization changed the continuous shear characteristics of the xanthan gum solution and the PPI-xanthan gum mixture. The continuous shear characteristics of PPI-chitosan and PPI-guar gum mixtures were altered by high-pressure homogenization at higher PPI concentrations (15% w/w). The storage moduli (Gʹ) of the mixed homogenates were frequency-dependent. High-pressure homogenization did not alter the elastic properties of the pure PPI suspension. However, the Gʹ changed in all three PPI-polysaccharide mixtures after high-pressure homogenization. Typical gel setting, gel weakening, and gel strengthening phases were observed in all the mixed homogenates except for the PPI-xanthan gum mixture, which did not show gel weakening. High-pressure homogenization changed the gelling time for most samples and induced gel weakening behavior in the PPI-xanthan gum mixture when the temperature was increased.

Effect of specific surface area of raw material Fe2O3 on magnetic properties of YIG

The effect of specific surface area (SSA) of Fe2O3 was investigated while evaluating the raw material of Y3Fe5O12 (yttrium iron garnet (YIG)) preparation. For YIG ferrite, the specific surface area of Fe2O3, rather than average particle size (D50), was found to markedly affect the mixing homogeneity of powders in the mixing procedure and the magnetic properties. Increasing the specific surface area of Fe2O3 resulted in the increase of the remanence (Br) and squareness ratio (SQR); meanwhile, it also caused an obvious reduction in coercivity (HC) for the sintered specimens. An upgrade in the specific surface area of raw material Fe2O3 could further resulted in a decrease in slurry viscosity in the mixing procedure, which promotes slurry mixing homogeneity and further promotes reactivity in the calcination and sintering processes. Consequently, a larger Br and SQR and a smaller HC were obtained. In addition, good ferromagnetic resonance (FMR) line width (i.e., ΔH) properties were also realized as 36.7Oe at 3.2GHz using the selected Fe2O3. As found in this study, the strict control of raw material Fe2O3 is critical in tailoring suitable Br and HC for the YIG ferrite manufacturing process.

Thermal expansion and thermal fluctuation effects in a binary granular mixture

Considering that in many practical problems thermal expansion and thermal perturbations are the factors that granular materials are often faced with, in this study the 3D numerical experiments based on the discrete element method (DEM) were first carried out to investigate their effects in a binary granular mixture at high temperature levels. The granular system consists of mixed ceramic and steel grains. The thermal expansion dynamics induced is analyzed in detail. Besides, the stress in pebbles (or force chains) inside the system was founded to be much relieved by temperature changes and force networks were subsequently degenerated in magnitude and space, especially under larger temperature change amplitudes. At the same time, the segregation between the statistical probability distributions of internal forces of the two grain components was also observed, reflecting that thermal perturbations have induced the density segregation between the two kinds of solid materials and damaged their mixing homogeneity in space. Moreover, the effect of friction was also studied. It was observed that friction can play the inhibiting role on the effects of both thermal expansion and thermal perturbations, but it would become insignificant once the friction coefficient exceeds one specific threshold value. These messages may provide important implications for the handling of granular materials.

Manufacturing and Evaluation of Local Animal Feed Mixing Machine

This investigation was carried out to develop and manufacture small animal feed mixing machine. Feed mixing machines are used in feed mills for the mixing of feed ingredients and premixes. The mixing machine is essential part in the feed manufacture, with accurate mixing being the key to good feed manufacture. The machine is small and works by very small power if compared with other machines. The goal of this experiment was to determine the optimum mixing duration at which the highest degree of mixing (homogeneity) is achieved. Experimental and designing studies were confined to determine the effect of mixing duration at constant speed of mixing drum, 228 rpm on coefficient of variation, degree of mixing (homogeneity), machine productivity, specific energy and mixing cost and the effect of moisture content of feed mixture on Pelleting efficiency. The machine was experimented and evaluated using four different mixing durations (5, 10, 15 and 20 minutes) and using different moisture contents of feed mixture (25, 28 and 31%). Results indicated that the mixer shaft was designed at a diameter of 20mm. The highest value of the performance parameters of the mixing machine and the optimum mixing duration was 5 minutes. The suitable moisture content of feed mixture for the following process which is pelleting process was 28%.

Optimization of geometric parameters of a ribbon impeller

Abstract Geometric parameters of a ribbon impeller were optimized on the basis of numerical calculations obtained from the solution of our own 3D/2D hybrid model. The optimization was made taking into account mixing power and homogenization time for ribbon impellers with a different number of ribbons and width operating in a laminar motion for Newtonian fluid. Due to minimum mixing energy required to stir a unit volume of liquid the most efficient impeller appeared to be that with one ribbon of width equal to 0.1 to 0.15 of the mixing vessel diameter. Impellers with more than one ribbon needed much higher mixing power but did not increase significantly secondary circulation in the vessel. These impellers increased first of all primary circulation, i.e. they increased only circular motion of liquid in the vessel.

Isotope geochemistry of Mississippi Valley Type stratabound F-Ba-(Pb-Zn) ores of Hammam Zriba (Province of Zaghouan, NE Tunisia)

The Hammam Zriba F-Ba-(Zn-Pb) ore deposit in the Province of Zaghouan in north-eastern Tunisia is hosted in the shallow dipping unconformity between green marls with chalky biomicritic limestones of Campanian age and Uppermost Jurassic carbonates. The mineralization consists mainly of fluorite and barite with minor sphalerite and galena. Calcite is the main gangue mineral. Two types of Zn-Pb sulfides can be distinguished according to the geometry of the orebodies, i.e., lenticular or stratiform ores, intra-karstic fillings. Sulfur isotope compositions (δ34S) of barite range from 14.7 to 17.2‰, indicating that sulfur was derived from Triassic evaporites and the higher ones (19–25.7‰) are due to reservoir effect associated with thermo-chemical sulfate reduction (TSR) or bacterial sulfate reduction (BSR) under conditions of restricted sulfate supply. δ34S of galena and sphalerite in lenticluar and intra-karstic orebodies range from −13.8 to 2.1‰, and could be explained by multiple sources of reduced sulfur: Triassic evaporites, diagenetic primary sulfides as well as sulfur from organic matter. Both TSR and BSR as potential contributors of sulfur are needed for sulfide precipitation. Lead isotope compositions of galena exhibit very similar: 206Pb/204Pb (18.858–18.876), 207Pb/204Pb (15.667–15.684), and 208Pb/204Pb (38.680–38.747) ratios, and plot between the upper crust and orogene average growth curves, reflecting involvement of a mixing and subsequent homogenization of Pb isotopic compositions of different source Pb reservoirs. The underlying Paleozoic basement rocks were the plausible source of metals. The economic ore (fluorite F1) mineralization was formed during the Eocene-Miocene compressional phase. During this deformation phase, deep-seated basinal brines have been circulated as hydrothermal fluids that have interacted with the Paleozoic rocks, thereby leaching metals, and have been channelized through subsidiary faults associated with the major regional NE–SW-trending deep-seated Zaghouan-Ressas fault. Hydrothermal fluids then migrated to the site of deposition where they got mixed with shallow, cooler, metal-depleted, TSR- and BSR-derived sulfur-rich fluids, which triggered the precipitation of the ores.

CFD modeling of styrene polymerization in a CSTR

A computational fluid dynamics (CFD) approach coupled with polymerization kinetics is implemented to investigate styrene polymerization using azobisisobutyronitrile (AIBN) as initiator and toluene as solvent in a lab-scale continuous stirred tank reactor (CSTR). The integration of kinetic model and CFD model taking molecular weight distribution into consideration is accomplished by a user-defined function (UDF) code using the method of moments. The results predicted by CFD compare with literature data satisfactorily. The effects of operating variables such as species diffusion coefficient, impeller speed, residence time and reaction temperature are analyzed. As the impeller speed increases, the degree of mixing homogeneity is improved, which results in decreasing conversion and molecular weight distribution. The proposed method can be used to predict polymerization behaviors in non-ideal mixing industrial reactors.

Effects of mixing state of composite powders on sintering behavior of cathode for solid oxide fuel cells

Abstract For efficient development of high-performance composite electrodes for solid oxide fuel cells (SOFCs), it is crucial to precisely tailor the microstructural features of the electrodes, such as their grain size, phase connectivity, and pore structure. Herein, we report the effects of the mixing state of component powders of a composite cathode composed of Sr-doped LaMnO3 (LSM) and yttria-stabilized zirconia (YSZ) on its sintering behavior. LSM-YSZ composite powders were synthesized by a particle-dispersed glycine-nitrate process using YSZ particles as inclusions in the LSM precursor solution. The dispersion state of the YSZ particles in the solution was varied from a well-dispersed state to a highly flocculated state through adjustment of the amount of adsorbed polyethylene glycol. The dispersion state of the component powders was found to strongly impact the densification behavior of the composite, which was explained by the formation of a continuous network of the “slow-sintering” inclusion particles. A highly porous structure with phase connectivity and sufficient triple phase boundaries could be achieved by enhancing the mixing homogeneity and optimizing the mixing scale. The proposed concept provides new insights into the microstructural evolution of composites in constrained sintering, and it could potentially enable development of the ideal electrode structure for SOFCs.

Experimental analysis of steam mixing and thermal stratification phenomena related to small steel containment studies

To study the mixing and thermal stratification caused by the plumes or buoyant jets in the small steel containment during the LOCA or MSLB accidents, temperature was measured experimentally. Using steam as the working medium, the experiments were conducted with various jet inlet temperatures and spray water flow rates to identify their influence on the thermal stratification phenomena. Temperature distributions with height are given to illustrate the thermal stratification in containment. The performed analysis shows that recirculating stratified fluid existed in only lower part of containment while steam mixing and temperature homogenization happened in upper part of containment. Rayleigh-Benard convection, which is often neglected in big steel containment stratification, and convection caused by negatively buoyant jet and plume entrainment are considered to be the major factors causing steam mixing. It is suitable to consider such thermal stratification and steam mixing in developing a more accurate and detailed model for small steel containment and system design of SMRs.

Quantifying Nanoparticle Mixing State to Account for Both Location and Size Effects

ABSTRACTRipley’s K function is commonly used to characterize the homogeneity of spatial point distribution. Not surprisingly, it becomes a favored tool in quantifying the nanoparticles mixing state in composite materials, a parameter that material scientists believe is of close relevance to certain properties of the nanoparticle-embedding material. Ripley’s K function assumes that the spatial points are dimensionless. In reality, the nanoparticles, once mixed in a host material, form clusters or agglomerates of various sizes and shapes. Our analysis shows that using the original K function falls short of ranking or distinguishing the homogeneity of nanoparticle mixing. We therefore propose to revise the K function to account for both particle location and size effects. We apply the revised function to electron microscopy images of material samples and conduct analysis and comparison of nanoparticle mixing. The analysis shows that the revised function is a better index to quantify the mixing states.

Hydrogenation of methyl acetate to ethanol by Cu/ZnO catalyst encapsulated in SBA‐15

The hydrogenation of methyl acetate (MA) is one of the important key processes for synthesis of ethanol from syngas. This work reports a highly efficient Cu‐ZnO/SBA‐15 catalyst prepared by facile solid‐state grinding method. Both copper and zinc species were encapsulated in SBA‐15 in high dispersion with the presence of organic template. The mixed homogeneity and interaction between copper and zinc species was enhanced as well with the help of organic template, resulting in the formation of Cu+ species in the reduced catalysts. Moreover, TOFCu(0) linearly increased with the Cu+/Cu0 ratio, indicating that a high proportion of Cu+/Cu0 induced by ZnO should be a key prerequisite to achieve favorable hydrogenation performance. It seems that the Cu+ species originated from Cu‐ZnOx species are more active than that from Cu‐O‐Si species in the activation of MA. These results may provide an inspiration in rational design of Cu‐ZnO‐based catalysts for esters hydrogenation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2839–2849, 2017

Effect of Injection Location and Multi-Hole Nozzle on Mixing Performance in a CNG-Fuelled Engine with Port Gas Injection, Using CFD Analyses

A compressed natural gas injection device with moving-coil electromagnetic linear actuator and mushroom type poppet valve was designed to supply a large-bore intake port injection type engine with sufficient fuel timely. The transient engine CFD model combined with the poppet valve's motion was established to research the effect of injection conditions on the mixing homogeneity in the intake port and cylinder. Computed penetration distances of impinging jet with different k-e models and different wall functions are compared with measured results in the literature to validate the model. It was observed that the gas injection location and number of nozzle holes have a significant effect on mixing performance both in the intake port and cylinder.

Macro-mixing characterisation of a stirred model fermenter of non-Newtonian liquid by flow following sensor particles and ERT

Investigation of the fluid circulation and the macro-mixing process in a stirred model fermenter of non-Newtonian liquid was conducted by the comparative use of flow following sensor particles, ERT and CFD. Average fluid circulation times were estimated from (i) the measured vertical position of the sensor particle, (ii) the fluctuating ERT signals of single ERT planes and (iii) the simulated dispersed phase. The estimated average circulation times of all the three methods are comparable for the two investigated impeller positions. Furthermore, axial residence profiles of the sensor particles were extracted, which reveal the impact of the impeller configuration to the axial mixing homogeneity. Moreover, the results confirm the conclusions about the effect of the off-bottom clearance of the impeller derived by Reinecke et al. (2012) in a 1000L pilot fermenter. The excellent detectability of the particles and the consistent results confirm the feasibility of the combined method for further investigation of the complex flows in biogas fermenters.

Effective of different homogeneous methods on physicochemical, textural and sensory characteristics of soybean (Glycine max L.) yogurt

ABSTRACTThe effect of ultrasonication (US), shear mixing (SM) and high pressure homogenization (HPH) on soybean (Glycine max L.) milk-produced set-type soybean yogurt was evaluated. The US treated with 280 W sample had the lowest water holding capacity value and highest syneresis value. Rheological constants were predicted by means of fitting the rheological model of non-Newton model. The soybean yogurt samples were found as a pseudoplastic fluid nature and the SM treated with 20,000 r/min sample had the highest apparent viscosity value and the US treated with 280 W had the lowest value. The HPH treatment caused a general decrease of hardness and adhesiveness in comparison to other samples. The overall acceptability scores of all the samples were above 6 on a scale of 1–10 indicating acceptability yogurts and the lower score in beany flavor for the yogurt might be partly due to the objectionable beany flavor still present in the samples.

Influence of Injection Angle and Valve Opening Manner on Mixing Performance in a Large-Bore Port Fuel Injection Compressed Natural Gas-Fueled Engine

One new kind of gas injection devices (GIDs), with moving-coil electromagnetic linear actuator (MCELA) and mushroom-type poppet valve, was projected to inject sufficient compressed natural gas (CNG) to a large-bore port fuel injection (PFI) engine. It had larger mass flow rate and better controllability than conventional GID. And the transient computational fluid dynamics (CFD) engine model incorporating the GID's motion was established to analyze the effects of the GID injection angle and poppet valve opening manner on the mixing homogeneity in the intake port, and finally, the in-cylinder mixing performance and gas movement intensity were compared. The results indicate that with the increasing of injection angle, the mixing homogeneity in the near-field injection location of intake port will be better, and the time when fuel starts to get into cylinder will be later. At ignition time, the injection angles 60 deg, 90 deg, and 120 deg show better in-cylinder mixing performance, while 150 deg has the worst. The pull-open GID injects more momentum to the intake port than the push-open one, and the mixing degree both in the intake port and cylinder is higher.

Influence analyses of mixing approaches on properties of conventional and interlocking-dense concrete

The main objective of this paper is to analysis the influence of mixing approaches on the properties of the conventional concrete (CC) and interlocking-dense concrete (IDC). Compared with the normal mixing approach (NMA), the two-stage mixing approaches (TSMA, including mortar mixed first (MMF), coarse aggregate wrapped with paste (CAWP), aggregate wrapped with cement (AWC)) were employed. The mixing homogeneity tests were conducted to evaluate the uniform of the fresh concrete with different mixing approaches. Moreover, compressive strength, flexible-tensile strength, flexible modulus and abrasion resistance tests were designed to evaluate the performance of the hardened concrete. Pearson correlation analysis and analysis of variance (ANOVA) was also involved to illustrate the correlation and differences between NMA and TSMA. The repercussion in the mixing homogeneity test shows that ΔG is a reasonable index to evaluate the uniformity of fresh concrete. This also reveals that the uniformity can be improved by TSMA for CC, while the MMF is the most effective approach to enhance the uniformity for IDC. The results help to find out that the most appropriate mixing approaches for CC and IDC are CAWP and MMF, respectively.

In-situ Cr-doped Alumina Nanorods Powder Prepared by Hydrothermal Method

Cr-doped ammonium aluminum carbonate hydroxide nanorods were prepared by a hydrothermal method, with Al(NO3)3·9H2O, Cr(NO3)3·9H2O, and urea as raw materials and PEG-20000 as surfactant. In-situ Cr-doped alumina nanorods powder was obtained through calcining its precursors (Cr-doped ammonium carbonate hydroxide nanorods) at 1200 °C. The crystal composition, the structure and the morphology of the as-prepared products were characterized by XRD, SEM and FTIR. Besides, the color performances of the products were analyzed by UV/Vis/NIR spectrometer and automatic color measurement. Results show that the precursors of Cr-doped alumina nanorods powder prepared by the hydrothermal method are composed of uniform nanorods. After its calcinations at 1200 °C, the in-situ doping of Cr in the alumina substrate is achieved. In the Cr-doped alumina nanorods powder, a continuous solid solution of Cr2O3 and Al2O3 is formed, which has a corundum crystal structure. With the increasing Cr content, Cr-doped ammonium aluminum carbonate hydroxide nanorods gradually become short, and the melting phenomenon occurs in calcined products. UV-Vis spectroscopy analysis shows that Cr-doped alumina nanorods powder has three strong absorption bands at 562, 406 and 372 nm, thus leading to a pink color for samples which is in agreement with chromatic data. In the present study, Cr-doped alumina nanorods powder prepared by the hydrothermal method can reduce the formation temperature of corundum crystal structures and resolve the problem of mixing homogeneity of Al2O3 and Cr2O3, which will contribute to the preparation and the application of alumina-chrome refractory, pink corundum abrasive and ceramic pigment.

Initial Drug Dissolution from Amorphous Solid Dispersions Controlled by Polymer Dissolution and Drug-Polymer Interaction.

To identify the key formulation factors controlling the initial drug and polymer dissolution rates from an amorphous solid dispersion (ASD). Ketoconazole (KTZ) ASDs using PVP, PVP-VA, HMPC, or HPMC-AS as polymeric matrix were prepared. For each drug-polymer system, two types of formulations with the same composition were prepared: 1. Spray dried dispersion (SDD) that is homogenous at molecular level, 2. Physical blend of SDD (80% drug loading) and pure polymer (SDD-PB) that is homogenous only at powder level. Flory-Huggins interaction parameters (χ) between KTZ and the four polymers were obtained by Flory-Huggins model fitting. Solution (13)C NMR and FT-IR were conducted to investigate the specific drug-polymer interaction in the solution and solid state, respectively. Intrinsic dissolution of both the drug and the polymer from ASDs were studied using a Higuchi style intrinsic dissolution apparatus. PXRD and confocal Raman microscopy were used to confirm the absence of drug crystallinity on the tablet surface before and after dissolution study. In solid state, KTZ is completely miscible with PVP, PVP-VA, or HPMC-AS, demonstrated by the negative χ values of -0.36, -0.46, -1.68, respectively; while is poorly miscible with HPMC shown by a positive χ value of 0.23. According to solution (13)C NMR and FT-IR studies, KTZ interacts with HPMC-AS strongly through H-bonding and dipole induced interaction; with PVPs and PVP-VA moderately through dipole-induced interactions; and with HPMC weakly without detectable attractive interaction. Furthermore, the "apparent" strength of drug-polymer interaction, measured by the extent of peak shift on NMR or FT-IR spectra, increases with the increasing number of interacting drug-polymer pairs. For ASDs with the presence of considerable drug-polymer interactions, such as KTZ/PVPs, KTZ/PVP-VA, or KTZ /HPMC-AS systems, drug released at the same rate as the polymer when intimate drug-polymer mixing was ensured (i.e., the SDD systems); while drug released much slower than the polymer when molecular level mixing or drug-polymer interaction was absent (SDD-PB systems). For ASDs without drug-polymer interaction (i.e., KTZ/HPMC systems), the mixing homogeneity had little impact on the release rate of either the drug or the polymer thus SDD and SDD-PB demonstrated the same drug or polymer release rate, while the drug released slowly and independently of polymer release. The initial drug release from an ASD was controlled by 1) the polymer release rate; 2) the strength of drug-polymer interaction, including the intrinsic interaction caused by the chemistry of the drug and the polymer (measured by the χ value), as well as that the apparent interaction caused by the drug-polymer ratio (measure by the extent of peak shift on spectroscopic analysis); and 3) the level of mixing homogeneity between the drug and polymer. In summary, the selection of polymer, drug-polymer ratio, and ASD processing conditions have profound impacts on the dissolution behavior of ASDs. Graphical Abstract Relationship between initial drug and polymer dissolution rates from amorphous solid dispersions with different mixing uniformity and drug-polymer interactions.